Very limited knowledge of the manufacturing of metal-matrix composite structures using rapid prototyping techniques currently exists. Two main approaches are known in the art for manufacturing of metal-matrix/ceramic composites. The first approach uses the direct sintering of metal/ceramic powders, and the second approach relies on the production of a three-dimensional ceramic preform followed by liquid infiltration of metals into the preform using high-pressure infiltration techniques.
Selective laser sintering (“SLS”) is an additive manufacturing technique that uses a laser as the power source to sinter powdered material (typically metal), aiming the laser automatically at points in space defined by a 3D model, binding the material together to create a solid structure. It is similar to direct metal laser sintering (“DMLS”); the two are instantiations of the same concept but differ in technical details. Selective laser melting (“SLM”) uses a comparable concept, but in SLM the material is fully melted rather than sintered. Any of these examples of the first approach, above, result in a high level of porosity within the sintered material, high internal stresses developed during the rapid prototyping process, and low speed of manufacturing (layer-by-layer deposition of materials) compared to the metal infiltration technique (the second approach, above). Although the second approach may thus be more useful than the first approach, this second technique is only applicable to a limited number of metallic materials.
In addition, the metal infiltration process (the second approach) requires the presence of interconnected pores within the ceramic preform. However, such pores are not readily achievable for complex geometries, and that unavailability of pores inversely affects the homogeneity of the mixture and the properties of the resulting metal-matrix composite. In addition, the second approach is accomplished in two separate and potentially involved steps, thus negatively influencing the time and cost efficiencies of manufacturing.